A multilayer LC complex component used in electronic circuits such as a high-frequency filter has such structures described in FIG. 6 and FIG. 7. FIG. 6(A) is a cross-section of a multilayer component of this kind, FIG. 6(B) is an exterior perspective view thereof and FIG. 6(C) is an equivalent circuit thereof. FIG. 7 is an exploded perspective view illustrating the state of the layers thereof. The background art of this kind, as described in FIG. 6(C), is an example of an LC complex component composing a so-called T-shaped filter. As described in FIG. 7, upper half ten layers comprise capacitor 10, and lower half six layers comprise inductor 12. Sheets A1 through A10 which comprise capacitor 10 are made of for example, dielectric substance, therein sheets A2 through A9 comprise a conductor for said capacitor.
Sheets B1 through B6 which comprise inductor 12 are made of, for example, magnetic substance, therein sheets B2 through B5 comprise a conductor for said inductor. A multilayer LC complex component is a multilayer substance which is produced by laminating, molding, pressing and firing those said sheets, and by forming terminal electrodes for external extension for said multilayer substance.
Next, each part of said multilayer LC complex component will be described with reference to the accompanying drawings. First of all, the explanation about capacitor 10 will be given. Sheet A1 is a protective layer. Conductor for capacitor D1 is formed on each of sheets A2, A4, A6, and A8. Conductor for capacitor D2 is formed on each of sheets A3, A5, A7, and A9. Said conductor for capacitor D2, a part of both front and rear side thereof is extended so as to be exposed on the surface of a multilayer LC complex component, is connected to GND electrode 14(side-mounted terminal) described in FIG. 6(B). Each of conductors for capacitor D1 is connected to one another through via hole D3 (indicated by contact lines) around the central part thereof: In other words, each of the said conductor for capacitor D2 has an aperture in the center thereof and through via hole D3 which passes through said apertures, each of the said conductor for capacitor D1 is connected to one another. Sheet A10 is a protective layer.
As described above, two patterns of conductors for capacitor D1 and D2 are alternately stacked, and each of the conductor for capacitor D1 is connected to one another through via hole D3. Capacitor C indicated in FIG. 6(C) is comprised of said conductors for capacitor D1 and D2.
Secondly, referring to FIG. 6 and FIG. 7, the explanation of inductor 12 will be given. Sheet B1 is a protective layer. On sheet B2, conductor for inductor E1 is formed for connecting inductor 12 to said capacitor 10. Said conductor for inductor E1 is connected to said capacitor 10 through via hole D3 which passes through sheet B1. On sheet B3, U-shaped conductors for inductor F1 and G1 are formed so that the openings thereof are facing with each other. One end of each of said conductors for inductor F1 and G1 is connected respectively to each end of conductor for inductor E1 through via holes F2 and G2.
On sheet B4, U-shaped conductors for inductor F3 and G3 are formed so that they are facing in opposite directions. One end of each of said conductors for inductor F3 and G3 is connected to conductor for inductor F1 and G1 respectively through via hole F4 and G4. On both ends of sheet B5, L-shaped conductors for inductor F5 and G5 are formed, so that the end of the extended part thereof is exposed on the surface of said multilayer complex component. One end of each of conductors for inductor F5 and G5 is connected to conductors for inductor F3 and G3 respectively through via holes F6 and G6. The bottom sheet B6 is a protective layer.
Of parts described above, conductors for inductor E1, F1, F3 and F5, and via holes F2, F4, and F6, all of which are connected so as to form a spiral shape, compose inductor LA indicated in FIG. 6(C). Conductors for inductor E1, G1, G3, and G5, and via holes G2, G4, and G6, all of which are connected so as to form a spiral shape, compose inductor LB indicated in FIG. 6(C). Conductors for inductor F5 and G5 on sheet B5, which are exposed at both ends on the surface of said multilayer component, are connected respectively to input/output electrodes 16 and 18 indicated in FIG. 6(B) and (C).
Said sheets, whereon said conductors for capacitor, said conductors for inductor, or said via holes are formed as described above, are stacked in the order indicated in FIG. 7, whereafter they are molded, pressed and burnt into a multilayer substance. By forming electrodes on front, rear, right, and left ends thereof, a multilayer LC complex component is produced. FIG. 6(B) is an exterior view thereof, providing a shape of rectangular parallelopiped. On both end planes of the longer plane thereof, input/output electrodes 16 and 18 are formed. Each of GND electrodes 14 are formed on the front and rear planes thereof. FIG. 6(A) is a cross-sectional elevation view of FIG. 6(B) which is seen in the direction of arrows along with line #6. As indicated in FIG. 6(A), via hole D3 provides a pillar shape in the central part of said multilayer substance, whereby an inductor device is connected to a capacitor device inside of said multilayer substance.
This background technology, however, causes deterioration of strength of said multilayer substance at this central part because via holes connected in series provide a straight pillar shape in the central part thereof. Especially, in such a case where a flexible substrate is used for on-board mounting, correspondingly large stress will possibly be exerted on said multilayer substance because the substrate itself is bent or warped. In more detailed description, an LC complex component mounted onto a substrate is soldered at both ends and at a side thereof. Therefore, the stress exerted by bending said substrate concentrates on the central part of the LC complex component. When there is a hole-contact in the center thereof, the part of hole contact is susceptible to cracking because a conductor filled inside of the hole has less resistance against bending than ceramic material around said conductor. A crack of said multilayer substance will permit entry of moisture inside thereof. This may deteriorate the quality thereof in such terms as moisture resistance.